Reinforced cathode-ray tube and face plate therefor



April 18, 1967 c. MINNEMAN ET AL REINFORCED CATHODE-RAY TUBE AND FACE PLATE THEREFOR 4 SheetsfSheet l Filed Dec.

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E y my# 7M Mm/J April 18, 1967 L.. c. MINNEMAN ET AL `HEINFORGED CATHODERAY TUBE AND FACE PLATE THEREFOR 4 Sheets-Sheet 2 Filed Dec. 18, 1964 IN VEN TORS C. M//VA/F//HA/ April 18, 1967 L c. MINNEMAN ET AL 3,314,566

REINFORCED CATHODE-RAY TUBE AND FACE PLATE THEREFOR Filed Dec. 18, 1964 4 Sheets-Sheet 5 ymwam,

April 18 1967 L.. c. MINNEMAN ET AL 3,314,566

REINFORCED CATHODERAY TUBE AND FACE 'PLATE THEREFOR Filed Dec. 18, 1964 4 Sheets-Sheet 4 FIG. 8

A-rToRN Eve Filed Dec. 18, i964, Ser. No. 422,063 27 Claims. (tCl. E20-4.1)

This is a continuation-in-part of application Ser. No. 285,696, now abandoned, led June 5, 1963.

This invention primarily relates to television and, more particularly, to the prevention of fracture and to the control of implosive-explosive effects in sealed and vacuumized cathode-ray image tubes such as for television reception.

More specifically, the invention relates to improved types of direct-viewing cathode-ray image tubes as well as other vacuumized tubes having glass envelopes of appreciable dimensions and methods of fabricating such tube envelopes to eliminate breakage and to control devacuation thereof upon accidental or spontaneous breakage either in processing, shipping, installation or while in service.

ln the manufacture of television picture tubes having essentially all-glass envelopes, each tube is evacuated to a high degree of vacuum with the resultant effect of creating high external pressures over extensive surface areas of the tube. Relative dimensions of these tubes are such that substantial surface pressures are exerted on the glass sidewalls and particularly on viewing and sealed portions. Such pressures cause vacuumized tubes to be highly subject to destructive implosive-explosive effects upon breakage or fracture of the glass envelope and sudden uncontrolled devacuation thereof. Therefore, the tube envelope and its various sealed areas are normally designed to safely withstand such high pressures without breakage during processing, shipment and installation as well as during long-term service.

Conventional television picture tubes are subject to variation in internal-external pressure conditions during initial fabrication of the tube and during reprocessing certain tubes found to contain malfunctions. Varying the pressure differential during evacuation, devacuation and re-evacuation, for example, may introduce excessive stresses into the tube envelope, particularly at their areas of maximum cross-sectional dimensions, such as where hollow funnel and face plate members are circumferentially joined at a seal line either by direct fusion or by an annular band of relatively low-melting glass sealing composition. Tensive stresses can and do occur in exterior surface portions of the envelope at or adjacent the seal line, which stresses must be controlled or avoided. Such stresses present localized areas subject to damage such as by scratches or abrasion which may result in envelope breakage. The envelope must be designed having sidewalls and seal construction to withstand such abrasive damage.

Previously in the installation of television picture tubes in various types of receivers, a transparent implosion plate usually consisting of a tempered glass panel has been mounted adjacent and fully coextensive with the tube viewing portion. Alternately, a contoured transparent implosion plate is bonded to the tube viewing area as an integral component part of the tube to resist implosiveexplosive effects. However, in both types of tube construction and mounting, whether the tube be unlaminated with a separate protective panel or laminated with an integral implosion plate, the tube may still be subject to destructive implosion, either spontaneously r by thermal or physical shock.

' United States Patent O In such implosions the glass of the envelope funnel sidewalls may break violently in such manner as to destroy the component parts of the receiver by fragments being projected forcefully in random directions. The implosion panel serves to restrain glass fragmentation in a forward direction as Well as to absorb frontal impacts delivered to the tube viewing area. However, in all cases either the separate or integral implosion plate adds substantially to the cost of the tube per se or its mounting in a receiver cabinet. Further, the implosion plate having substantial dimensions and wall thickness adds to the overall weight and dimensions of the receiver, and in combination with the tube face plate must provide proper light-transmitting characteristics while protecting viewing areas against implosion.

Obviously, in conventional types of essentially allglass cathode-ray picture tubes for television reception, only the viewing area has been previously protected against implosion when the tube is properly installed. The body portion of the tube envelope remains subject to damage either in processing, installation, or when the receiver is serviced. The frontal implosion panel does not serve in any way to prevent damage to the tube body portion but merely protects against deleterious effects from or in a forward direction. The implosion panel must have light-transmitting properties of near-optical clarity and no visual defects can be tolerated in either this panel or the tube face plate. Near-optical perfection and strength requirements in these several members necessitate special precautions in their forming and handling. The present invention obviates the need for the conventional twin-panel system and optical matching of these component parts.

Accordingly, it is an object of the present invention to provide a reinforced direct-viewing vacuum tube envelope which is damage-resistant and capable of controlling sudden devacuation without serious fragmentation of its sidewalls under widely-varying adverse conditions.

Another object of this invention is to provide an improved type of reinforced glass vacuum tube envelope which is capable of withstanding tube fabricating processes, the envelope having resistance to fracture and inherent control over its sudden devacuation wherever and however caused, the completed tube being adapted to further reinforcement at the periphery of its viewing area and capable of functioning in a normal manner.

Another object of this invention is to provide a novel implosion-proof cathode-ray image tube envelope which is capable of being fabricated into La completed tube having integral heat-resistant reinforcing means to resist thermal damage and implosive-explosive effects, said reinforcing means extending over non-Viewing exterior surfaces adjacent its viewing area to eliminate exterior surface damage thereat and to prevent violent devacuation of the envelope.

An additional object of the present invention is to provide a face plate having heat-resistant reinforcing means extending over non-viewing surfaces adjacent the viewing area, said reinforcing means being capable of withstanding thermal cycling during tube making process and facilitating the addition of heat-destructible components to the completed tube in supplemental operations.

Another object of this invention is to provide resistance to fracture and breakage in a hollow glass envelope utilized in the formation of large-size Vacuum tubes and the like, wherein said envelope possesses heat-resistant integral means to control and minimize sidewall fragmen-.

tation upon rapid devacuation due to spontaneous or accidental breakage.

A further object of this invention is to provide a directviewing implosion-resistant television picture tube en- 3 velope, the forwardmost non-viewing external surfaces adjacent the envelope viewing area having implosion and fracture preventing elements disposed annularly thereover to minimize sidewall fragmentation upon envelope breakage.

A further object of this invention is to provide a method of fabricating an electron-discharge tube envelope having integral reinforcing components surrounding peripheral sidewalls of essentially maximum cross-sectional dimensions of the envelope, said reinforcing components being capable of withstanding thermal cycling during tubemaking processes and facilitating the addition of heatdestructible components to the completed tube in supplemental operations.

A still further object of this invention is to provide a new article of manufacture and method of fabricating Same to provide a primarily-glass electrical discharge tube envelope having heat-resistant elements surrounding a non-viewing frontal region of subtsantial dimensions whereby upon breakage the envelope is permitted to controllably devacuate without deleterious fragmentation of its sidewalls.

The specific nature of this invention as well as other objects and advantages thereof will become apparent to those skilled in the art from the following detailed description taken in conjunction with the annexed sheets of drawings on which, by way of preferred example only, are illustrated the preferred embodiments of this invention.

In the accompanying drawings:

FIGURE 1 -is a perspective view of a cathode-ray television picture tube fabricated in accordance with the present invention;

FIGURE 2 is an enlarged fragmentary view partly in vertical section of the tube envelope taken along the line 2-2 of FIGURE 1;

FIGURE 2a is a view similar to FIGURE 2 taken along the line Zar-2a of FIGURE 1;

FIGURE 3 is an exploded View illustrating the individual components utilized to fabricate the embodiment shown in FIGURE 1;

FIGURE 4 is an enlarged fragmentary view similar to FIGURE 2 illustrating a modification of the invention;

FIGURE 4a. is a view similar to FIGURE 2 illustrating the same embodiment with the band sealant in place;

FIGURES 5 and 6 are views similar to FIGURE 4al illustrating several additional modifications of the invention;

FIGURE 7 is a view similar to FIGURES 2 and 4 illustrating a still further embodiment of the invention.

FIGURES 8, 9 and 9a are views similar to FIGURE 1, 2 and 2a showing a face plate fabricated in accordance with the present invention prior to the joinder of the face plate to the funnel member.

The present invention is described hereinbelow as specifically applied to the manufacture of a television cathode-ray picture tube, however, it will be apparent to those skilled in the art that the invention is equally applicable to the manufacture of many different types of evacuated tube envelope particularly all-glass envelopes having substantial dimensions which are subject to implosion and concomitant explosion on sudden devacuation.

The term devacuation as used herein is intended to mean the converse of evacuation as in the case where a vacuumized vessel experiences an internal pressure change toward atmospheric pressure upon loss of vacuum. The rate of change may occur rapidly or over an extended period of time wherein the evacuated space interiorly of the envelope returns to atmospheric pressure.

The present invention provides an impact-resistant and implosion-proof system which is capable of being incorporated into existing types and shapes of cathode-ray tube envelopes without serious alterations or modications -of present tube fabricating procedures. Certain elements of the invention are combined with the selected type of glass bulb or envelope using materials and methods which are capable of supplementing envelope fabricating processes. Only minor additions to the system are required subsequent to conventional tube fabricating processes. As used herein, the term bulb is applicable to the tube en- Velope per se, while the term tube refers to the envelope hermetically-sealed in evacuated condition with its addit-ional electrical and image-producing components properly installed in operative arrangement.

Briey stated, the invention involves the application of a high-tensile strength contoured annular band which is snugly mounted around a perimetrical region of the tube face plate surrounding its non-viewing exterior surfaces of substantially maximum cross-sectional dimensions. The annular band has internal surfaces which are precisely complemental to forwardmost non-viewing exterior surfaces of the envelope and is mounted transversely of its axis. An intermediate circumferential space is provided between the contoured band and the envelope exterior surfaces preferably at a non-viewing region adjacent the transitional Zone where the periphery of the tube viewing area joins a surrounding perimetrical and axial-extending sidewall. A second annular band is placed around the tube envelope surrounding and at least partially overlapping a rearward annular portion of the first-applied contoured band. The second band also encompasses and surrounds envelope sidewalls disposed adjacent and rearwardly of the rst band. Both bands are preferably disposed enirely forwardly of the annular seal line region where face plate and funnel members of the envelope are circumferentially joined. By virtue of such location the bands may be applied either before or after the face plate and funnel member are joined to form the bulb. This is especially signicant in the manufacture of color television tubes where present technology dictates that the face plate and funnel members be shipped separately to the tube fabricator who installs the electrical and image-producing components and then joins the face Iplate to the funnel member. As is well known in the art of fabricating color television tubes, these members are joined and sealed by an annular band of relatively lowmelting glass sealing composition.

The several annular bands are heat-resistant and capable of withstanding conventional thermal bake-out and evacuation cycles of cathode-ray tube making processes. After the tube is fully fabricated into final form, an annular layer of adhesive material such as synthetic resin is introduced into an intermediate circumferential space to provide a continuous perimetrical bonding layer. A single contoured annular band having proper physical characteristics such as thin-walled high-tensile strength metal can also be employed to perform functions of the several individual bands as desired or required. The forwardmost band has an annual contour which is precisely coinplemental to major surrounded envelope exterior surfaces where applied. This band is preferably endless in character and applied to the envelope in continuous tension by expansion and contraction of the band. The circumferential space is provided adjacent the frontal edge of the single band and subsequently filled with a bonding medium.

In a preferred embodiment of the present invention as shown in FIGURE l, a glass cathode-ray tube envelope l@ is normally comprised of a funnel member 11, face plate 12 and neck tubulation 13 which are joined to form a unitary hollow glass article. The terminating end of neck tubulation 13 is normally sealed by one or more electron-beam emitting guns retained within an end cap member 14. Funnel member 11 is usually frusto-concial or frusto-pyramidal (FIGURE l) in shape with its small end 11a sealed to neck 13 and its large end 11b sealed to face plate 12. Electromagnetic beam deiiecting coils (not shown) are normally mounted -at the yoke area where neck 13 and funnel small end Illa are joined t0 provide electron beam deflection and proper scanning of the tube screen.

Face plate 12 consists of a concavo-convex viewing portion 12a bounded by a depending peripheral side panel or ange 12b (FIGURE Z). Face plate flange 12b and large end 11b of the funnel member terminate in annular sealing surfaces of generally complemental planar contour. Sealing surfaces are joined at seal line 15 either by direct fusion of the glass or by an interposed annular layer of solidified low-melting glass sealing composition which is selected as being compatible with the thermal and physical characteristics of the parent glass parts. The basic shape of the enevolpe viewing area 12a may be either rectangular (FIGURE l) or circular (not shown) in plan as conventionally known in the art with the sealing surfaces being substantially planar for forming a vacuum-tight durable joint. However, the present invention is applicable to all conventional types of cathoderay tube envelopes regardless of their contours or dimensions.

As stated, the invention consists of applying certain heat-resistant reinforcing elements to external nonviewing surfaces of the tube envelope prior to subjecting the envelope or bulb to a tube fabricating process, it 4being understood that such reinforcing elements may be applied either before or after the face plate is joined to the funnel member. The initially-applied reinforcing elements Iare capable of withstanding temperatures of the order of about 450 C. for a sufficient length of time to conduct bake-out and evacuation cycles in fabricating the completed tube without degradation of these elements. The bulb after being fabricated into this form exhibits certain characteristics for controlling devacuation on breakage, however, as described hereinbelow one or more additional elements is applied to the enevlope subsequent to its conversion into a completed tube to further safeguard the same. The components initially applied to the bulb to provide implosion and fracture resistance must be capable of withstanding required bake-out cycling temperatures and pressures of the tube-making process while the components subsequently applied to the tube need not be capable of withstanding such severe environments.

' Method of fabrication A glass face plate 12 of an all-glass cathode-ray image tube envelope or bulb 10 having an open-neck tubulation I3 excluding end cap ld is taken for further fabrication and reinforcement in accordance with the following method. As shown in FIGURE 3 illustrating the ein-bodiment wherein the reinforcement is applied to an assembled bulb, a peripheral rim band which is preferably comprised of two similar metallic half-sections 20a and 20h is taken for mounting on the face plate corner area 12e. Alternately, a unitary annular band having prescribed cir cumferential dimensions is employed. Each of the two half-sections 20a and Ztlb is contoured to have internal surfaces which -are closely complementa] to the geometry of about one-half the external surfaces of face plate annular corner 12e. Corner surfaces lZc lare formed by the transition zone `between the periphery of viewing panel 12a and surrounding perimetrical flange 12b. Each half-section has a U-shaped configuration and a circumferential extent slightly greater than one-half the periphery of face plate corner surfaces 12C. The pair of similar bands preferably overlap in telescoping arrangement on opposing sides of the face plate such las on the short axis side of the rectangular enevelope. The pair of bands are premeasured to determine their precise circumferential extent in mounted relation. ln one embodiment the pair of half-sections are fitted around the complementally-contoured corner surfaces 12e of the `face plate with their end portions in juxtaposed overlapping relation. Half-sections 20a and 2Gb overlap on the short-axis opposing sides of the face plate at line 20e. The bands are marked at the overlapped region while snugly disposed around the face plate in telescoped relation and then are removed therefrom. The overlapped portions of the removed half-sections are then shortened a prescribed distance such as 0.160 inch on each side at line 20e for a 23 diagonal inch rectangular bulb. The several sections are then joined into a unitary annular band such as by spot-welding at each side. With a plurality of envelopes having precise exterior surface contours at their frontal region, one-piece bands having the requisite slightly lesser circumferential dimensions lare utilized.

A forward portion of rectangular rim band 20 has an exteriorly-projecting annular beaded region 20c formed on its opposing sides to provide a circumferentiallydisposed recess 21a intermediate the band and corner surfaces 12C. As shown in FIGURE 2, annular space 21a extends throughout the extent of long and short-axis sides of the face plate. The exteriorly-projecting beaded :region 20c defining the recess 21a feathers at the corner regions of the face plate into two parallel beaded regions 20d defining a pair of spaces or channels 2lb. Thus, a pair of spaces or channels 2lb connecting with space 21a are provide-d at the corner regions intermediate the band and face plate corner surfaces 12C. Such construction insures that suicient space exists *between the sidewall and the beaded regions 20d to permit the introduction of a sufficient quantity of adhesive material to insure firm bonding between the band and the peripheral sidewall in this critical area. The circumferential space is located anywhere between frontal and rear edges of the contoured band and preferably slightly rearwardly of the corner radius on the long-axis sides and closely adjacent the corner radius on the short-axis sides and at the corners of a rectangular face plate when viewed in plan.

With annular band Ztl formed as described having a circumferential extent slightly less than face plate annular corner surfaces 12C, the band is `heated into expanded condition such as by surrounding it with a high-frequency electrical heating coil. Band 20 is comprised of relatively thin-walled hightensile strength metal such as carbon steel having an aluminum metal coating thereover to minimize or prevent oxidation on mod-crate heating. With the band in expanded condition it is capable of being fitted over corner surfaces 12C and allowed to cool therein into shrunken condition. The band in cooled form at ambient temperatures is then placed in tension to introduce compressive stresses into the glass sidewalls therebeneath. Band 20 preferably is placed in tension in the range of 300 to 400 .pounds such that it tends to a-pproach its yield strength at the corner regions of the lbulb due to minimal cross-sectional dimensions thereat. Band 20 has a frontal edge configuration which conforms snugly to the non-viewing periphery of the viewing area 12a and parallels the so-called screen line of viewing area 12a. This frontal edge is preferably spaced about "/16 inch from the screen line for a 23 inch tube. The rearward edge of 'band 20 extends adjacent and parallel to the mold match line 12d of the face plate.

A series of access openings or apertures 20f are provided at spaced-apart locations in lband 20 such as at the midpoint of the long and shortaxis sides. These apertures :may be provided in band 20 when fabricated or may be formed in its beaded region 20c after the band is properly applied to the envelope. The plurality of apertures serve to facilitate the introduction of an adhesive or bonding material into annular spaces 21a and 2lb to permanently bond band 20 to exteriorl surfaces 20c.

As shown in FIGURES l, 2 and 2a, immediately subsequent to mounting band 20 in tension surrounding envelope exterior surfaces 12e, tension band 22 such as one comprised of thin-walled heat-resistant metallic material is applied to the envelope yband 20. Band 22 preferably is comprised of tempered canbon steel strapping having a coating of aluminum metal thereover. Band 22 encompasses and surrounds a rearward portion of band 20 as well as an adjacent exterior surface of the 7 envelope. Band 22 is mounted to straddle mold match line 12d of the face plate and both bands 20 and 22 are mounted forwardly of seal line 15. Band 22 preferably consists of a discontinuous element having its ends joined by a clip member 23 or joined at a localized region by spot-welding.

In a preferred embodiment, tension band 22 overla-ps rim band Ztl by about one-half inch and cons-ists of a flexible strap of substantially uniform cross-section. A tensioning device such as an air rwrench is employed to draw band 22 into permanent tension with the ends of the bands passed through clip Vmember 23 which is crimped to form a permanent connection of the band ends. Band 22 may also be comprised of an endless ring member `which may be shrunk onto the rim band and adjacent envelope surfaces. Band 22 is preferably placed in tension ranging from about 800 to 1500 pounds tension for a 23 inch tube. FIGURES 2 and 2a illustrate in sectional views the disposition of the several bands at long side and corner areas of the envelope. FIGURE 3 illustrates the several bands individually in an exploded view prior to their mounting on the envelope.

FIGURES l, 2 and 2a illustrate a tube envelope having the metallic reinforcing elements surrounding a nonviewing frontal region of the envelope. Both bands are mounted in a transverse plane substantially parallel to seal line 15 and `forwardly thereof and, as `shown in the drawings, rim band has a greater width on its long axis sides than on its short axis sides. Normally, this member has its narrowest width at the corner regions due to conventional face 4plate contours. The envelope having the several bands mounted thereon is capable of providing abrasion resistance to the envelope exterior surfaces where mounted as well as providing substantial implosion resistance against `breakage due to im-pacts of the order of about five foot-pounds delivered to any -region of the tube face. The all-glass envelope in this condi- Ation is capable of being taken to a tube fabricating process and withstanding all ther-mal bake-out and evacuation cycling without deleterious effects on its metallic reinforcing members.

As shown in FIGURE 4, only a single annular rim band 20 is utilized to surround the face plate corner surfaces 12C. In this case band 20 has a configuration Similar to that shown and described in FIGURES l and 2 and provides an open ann-ulus 21a and 2lb at the transitional zone between the viewing panel 12a and perimetrical ange 12b. Band 20 may also have a longer axial extent rearwardly to surround and encompass greater surface areas of sidewall -portion 12b. However, where only a single band is employed, the circumferential open space is provided in generally the same area as described hereinabove.

The subject envelopes When evacuated are capable 0f controlled evacuation on breakage of the envelope. The tubes can be subjected to nominal impact damage which may or may not be perceptible at normal viewing distances. The described elements are capable of safeguarding the envelope against destructive implosiveexplosive effects on breakage due to moderate adverse effects. However, further reinforcement thereof is highly desirable in order to make the envelope resistant to both high and low impact damage as Well as breakage caused by any and all sources.

Tube envelopes fabricated as shown in FIGURES 2 or 4 are then subjected to a tube fabricating process in order to install the Working components of the completed tube. This involves the application of one or more luminescent screen materials to the interal surface of viewing -area 12a, a conductive coating over non-viewing internal surfaces of the envelope, the installation of the cathode-ray emitting gun or guns and evacuation of the envelope, all of which operations are conventionally known in the art and do not comprise a part of the present invention. The tube is then finally formed with all of its internal and external working components properly in- O c; stalled in operative alignment following which it is subjected to bake-out temperatures and evacuation.

The completed tube is then subjected to the application of one or more additional elements in accordance with this invention with ambient conditions existing externally of the tube. As stated, an organic adhesive capable of integrally bonding glass-to-metal surfaces is introduced into this space subsequent to the tube-making process as described hereinbelow.

A completed cathode-ray picture tube capable of recreating transmitted electronic images is taken for further reinforcement of the envelope in accordance with the following procedure. The series of access openings Zlf such as at the mid-,points on the long and short axis sides of the envelope are utilized to introduce an adhesive bonding material such as epoxy resin into the interconnecting annular spaces 21a and 2lb. Either an individual pressurized gun or a manifold having an aligned series of discharge orifices is employed to introduce the synthetic resinous material interiorly of the circumferential space. A continuous annular layer 24 of synthetic resin, such as epoxy or polyester resin, as shown in FIGURES 4a, 5 and 6, is introduced into the open annulus. Good adherence of annular bonding layer 24 to both 4the glass and surrounding rim band surfaces is particularly important. A preferred material consists of Union Carbide Epoxy Resin, Product No. EXRL-023 l-A, this particular resin ysystem having a relatively high viscosity when previously mixed with two parts Union Carbide Hardener, Product No. EXRL-O23 l-B per one part of a resin. The subject resin is a thixotropic resin system manufactured by Union Carbide Company for sealing glass-to-glass and glass-to-metal members. The epoxy system is comprised of liquid epoxide resin which can be cross-linked by a liquid hardener into a tough, Aresistant solid having excellent dimensional stability and strength. The reactive resin system forms a stable, durable adhesive bond between glass and metal. An epoxy resin which is particularly well suited for this purpose is Union Carbide Epoxy No. EBLM 7652 which yis also a thixotropic paste having a relatively high viscosity when mixed two parts Union Carbide Hardener No. ABLM 8653 per three parts resin. This resin system has an elongation at rupture of l percent and will eure at room temperature in three to four hours or at 200 F. in ten minutes. Other liquid epoxy resins which are lrelatively thick and capable of being pumped under pressure can also be employed. The syntheic resin system is capable of bonding chemically to the glass surfaces or reaction, the nal rigid layer having a considerable strength for rupture resistance. If desired, a high-temperature resistant bonding agent can be similarly employed.

As shown in FIGURES 5 and 6, annular `layer 24 essentially fills the previously open annulus 21a and 2lb and extends in a circumferential pattern throughout the peripheral extent of corner surface 12C. FIGURE 6 shows both bands 20 and 22 disposed in place and maintained in tension as described hereinabove with continuous bonding layer 24 filling the intermediate space between band Ztl and exterior surfaces 12C. FIGURE 5 illustrates 4only a single rim band 20 in place with a simi- -lar annular layer 24 of bonding material therebeneath. As shown in both views, a surrounding layer 25 of glass ber cloth impregnated with an intermediate layer of synthetic resin 26 such as epoxy resin is employed ,to surround the funnel. The layer 25 of interwoven and adhered material may :be Iapplied over extensive major ex. terior surfaces of the funnel member extending forwardly to adjacent mold match line 12d and metal bands 20 and 22. The supplemental layer of woven material such as glass ber cloth may or may not be applied as required, depending upon the shape and size of the envelope and the desired level of damage resistance desired. The application of adhered interwoven material 25 to the funnel strengthens the envelope against most lsevere impacts, however, elimination of this element permits the banded bulb to resist low and moderate damage levels in an acceptable manner.

FIGURE 7 illustrates another form of the invention in which non-viewing exterior surfaces of the glass face plate have an annular recess 12e formed in an area adjacent corner radius 12e. Contoured band 20 has a smoothly-curved internal surface devoid of an exteriorlyprojecting beaded portion to sungly surround corner surfaces 13C and mold match region 12d. Thus, with band 20 disposed in place and in continuous tension, an open annulus 21C is provided within which is disposed an annular layer of adhesive m-aterial. The tension band 22 contacts and surrounds the rearward portion of band 20 to reinforce the same.

One of the tension bands such as contoured rim band 20 or 20 may have a series of spaced-apart lug members 30 (as shown in broken outline in FIGURE 2A) mounted thereon in exteriorly-projecting relation. The lug members `are preferably L-shaped in cross-section and located at the four corners of the tace plate when viewed in plan to facilitate retention of the tube in a receiver cabinet. Lug members 30 also serve to provide a seat for tension band 22 to permit its expedient mounting in a plane transversely of the envelope axis parallel to the rim band. FIGURES 8, 9 and 9a illustrate a form of the invention in which the reinforcing elements, either the single rim band 20 or the rim band 20 and tension band 22, are applied to the face plate 12 prior to the joining of the face plate to the funnel member 11.

The above-described reinforcing elements which consist of a pair of circumferential bands provide a system of reinforcement which will withstand prolonged exposure to 450 C. without deterioration of the system. The use of heat-resistant aluminized steel bands is preferred to minimize or prevent yoxidation of these elements on heating. The rim band is sweated on to apply approximately 300 to 400 pounds tension an-d the second tension band applies an additional 800 or more pounds tension to the envelope. The endless rim band is shortened by about .0320 inch for a conventional 23 diagonal inch tube. The glass `sidewalls therebeneath are thus placed in considerable compression.

The combination of 0.021 inch thick sweated rim band and a three-quarter inch wide 0.035 inch thick tension band was applied to a twenty-three inch tube envelope having the construction shown in FIGURES l, 2 and 2a. In this case no adhesive was used to bond the rim band to the glass exterior surfaces. A tota] of 46 bulbs were impact-tested at various foot-pound impact levels in different positions on the face. Of this test group, 29 were subjected to ve foot-pound impacts which produced small fissures in the face and resulted in about 100 to 200 times less glass being thrown forwardly as compared with a plain unreinforced cathode-ray television tube envelope of the same type. Of seventeen foot-pound impacts, six caused cave-in type devacuation which resulted in approximately ve times less glass being thrown forwardly as compared with a plain cathode-ray television tube envelope of the same type. Without an annular layer of resin to obtain rm adhesion of the rim band, some fragments of glass are thrown forwardly at the 15 foot-pound impact level and above. The subject bulb is resistant to violent devacuation due to thermal shock and guillotine tests.

With an epoxy resin injected into the annular space beneath the contoured rim band to provide a well-cemented rim band construction, a total of 120 bulbs were tested and evaluated at all positions. Impact forces were varied from five to 50 foot-pounds. Twenty-tive tive foot-pound impacts produced small fissures in the face with only small slivers of glass falling off the face section. This same test applied to Iplain television tubes of the same type results in hundreds of times more glass being thrown forwardly. Sixty-five bulbs were tested with 15 footpound impacts which caused 30 cave-in devacuations, and

produced 20 times less glass being thrown forwardly for the cave-ins than a plain television tube of the same type would throw when subjected to the same test. Twelve 25 foot-pound impacts at center position resulted in approximately 1,000 times less glass being thro-wn forwardly as compared to a plain television tube of the same type under the same conditions. Thirty-tive and fty footpound impacts delivered in the center portion were conducted. Three out of eleven 50 foot-pound impacts caused safe cave-in devacuation with approximately ve to ten times less glass being thrown forwardly as compared to a plain television tube of the same type under similar conditions. The remaining eight tubes tested resulted in virtually no glass being thrown forwardly. The system performs very well when subjected to thermal shock and guillotine-typer tests.

The subject system controls devacuation caused by tive foot-pound impacts delivered at any region of the face. With the addition of the epoxy resin adhesive in bonding relation, the system is perfectly safe when tested with 15 foot-pound impacts delivered at any position except when struck closely adjacent the rim. band at a corner location. Additional testing of 24 bulbs with 25 to 50 foot-pound impacts delivered at the center position resulted in safe devacuation. The corner impacts were considered to cause destruction of the system due to probable release of the tension in one or both bands. When tension is maintained in both bands during breakage, safe devacuation from any cause with minimal glass throw `is observed.

Cathode-ray tubes fabricated in accordance with the above-desired invention possess signiiicant weight advantages due to their being direct-viewing with no separate or integral implosion panel being required. The subject tubes are wholly capable of controlied devacuation on breakage of the envelope whether subjected to nominal or severe impact damage or other adverse effects such as thermal shock. The subject tube envelopes are able t0 control their devacuation on sud-den or accidental breakage and attendant release of vacuum under virtually all forms of destructive damage. The non-viewing periphery of the face plate viewing area is completely restrained against movement either laterally or radially on envelope breakage, -however caused, by the surrounding reinforcing elements. On cavitation of the face plate from any fracture source, fragments of the viewing area are driven with less force in a rearward direction by atmospheric pressure to strike and impinge upon internal surfaces of the funnel member. The face [plate fragments may or may not cause breakage of the funnel from internal impingement due to retardation of impact forces achieved by retention of the face plate perimeter. The reinforced peripheral corner and adjacent ange of the face plate are positively maintained completely intact in breakage and crack propagation through this region is markedly reduced or elimniated. The space intermediate the rim band being filled with reacted adherent rupture-resistant material functions to maintain the envelope sidewall regions therebeneath in integral form. Although cracks or ssures may be created in the envelope sidewalls at the area of centrally maximum cross-sectional dimensions reinforced against movement due to breakage originating at any region, collapse of the envelope is delayed or retarded so that air cannot rush into the interior void to cause rapid and destructive fragmentation. Thus, retardation of air `rush-ing into the vacuumized interior from either the face plate or funnel areas is achieved to prevent violent devacuaticn of the envelope. In most cases fracture of the face plate usually results in minimal fragments being drawn inwardly with virtually their complete containment within the funnel. Where the funnel is broken, fragments thereof which impinge the interior surfaces of the face plate may cause breakage thereof. However, the throw of fragments is greatly retarded or eliminated.

l ll

Various modifications may be resorted to within the spirit and scope of the appended claims.

We claim:

1. As an article of manufacture, a cathode-ray tube envelope comprising a substantially funnel-shaped hollow body member and a light-transmitting viewing member enclosing its larger end, said viewing member having an integral yperipheral sidewall portion of substantially maximum cross-sectional dimensions of said envelope sealed to the larger end of said body member, at least one endless reinforcing band of thin-walled high-tensile strength material surrounding the peripheral sidewall portion of said viewing member and complementally contoured to conform snugly to its forwardmost non-viewing region, said reinforcing band being maintained in continuous tension to introduce compressive stresses into the peripheral sidewall portion therebeneath, a circumferential open annulus located intermediate said band and the exterior surfaces of said envelope sidewall portion therebeneath, and at least one access opening into said open annulus to facilitate the introduction of adhesive material thereinto subsequent to mounting said band.

2. A cathode-ray tube envelope in accordance with claim 1, wherein an annular recess is provided in the internal surface of said endless reinforcing band to form said open annulus.

3. A cathode-ray tube envelope in accordance with claim 1, wherein an annular recess is provided in the external surface of said envelope peripheral sidewall portion adjacent its forwardmost non-viewing region to form said open annulus.

4. A cathode-ray tube envelope in accordance with claim 1, including a plurality of access openings disposed in spaced-apart symmetrical relation within said reinforcing band.

5. As an article of manufacture, a cathode-ray tube envelope, comprising a substantially funnel-shaped hollow body member and a light-transmitting viewing member enclosing its larger end, said viewing member having an integral peripheral non-viewing sidewall portion of substantially maximum cross-sectional dimensions of said envelope sealed to the larger end of said body member, at least one endless reinforcing band of thin-walled hightensile strength metal surrounding the peripheral sidewall portion of said viewing member and complementally contoured to conform snugly to the forwardmost nonviewing sidewall portion, said contoured reinforcing band having at least one annular recess in an inner surface to provide a circumferential space extending transversely of the envelope axis intermediate said band and the exterior surfaces of said sidewall portion therebeneath, said rein- -forcing band being maintained in continuous tension to introduce compressive stresses into the envelope sidewall portion therebeneath, said contoured band having at least one access opening extending into said annular inner recess to facilitate the introduction of adhesive means interiorly of said circumferential space.

6. A cathode-ray tube in accordance with claim wherein said viewing member has a generally rectangular configuration and means are provided for maintaining the space between said band and said sidewall exterior surface in the corner regions of said rectangular viewing member.

7. A cathode-ray tube envelope in accordance with claim 5 wherein said reinforcing band is comprised of a pair of similar U-shaped half-sections integrally joined at diametrically-opposed locations and having a circumferential extent slightly less than the surrounded periph- -eral sidewall portion of said viewing member at ambient temperatures.

8. A cathode-ray tube envelope in accordance with claim 5 including a second discontinuous reinforcing band surrounding an annular rearward portion of said first contoured reinforcing band, both said bands being mounted entirely forwardly of said envelope body member, said second reinforcing band being maintained in continuous tension to maintain said rst band in snug conformity to und the non-viewing peripheral sidewall region of said envelopo viewing member.

9. A cathode-ray tube envelope in accordance with claim 5 including a series of spaced-apart access openings disposed in said rst contoured band.

1t?. A cathode-ray tube envelope in accordance with claim 5 including a continuous annular layer of reacted epoxide resin containing adhesive material substantially filling said circumferential space.

li. A cathode-ray tube envelope resistant to implosiveexplosive effects upon breakage comprising a substantially funnel-shaped glass body portion and a light-transmitting glass viewing portion enclosing its larger end, a first endless metallic reinforcing band closely surrounding the non-viewing periphery of said envelope viewing portion complementally contoured to conform snugly to the exterior surfaces of said envelope and disposed normal to its axis, said first reinforcing band having at least one beaded region of enlarged exterior dimensions extending annularly to provide a circumferential space intermediate said band and the exterior surfaces of said non-viewing periphery therebeneath, a series of exetriorly-opening apertures in the beaded region of said first reinforcing band to facilitate the introduction of adhesive material within said circumferential space, a second discontinuous metallic reinforcing band surrounding at least an annular rearward portion of said first band, and means for maintaining said second band in continuous tension, both said first and second reinforcing bands being disposed entirely forwardly of said envelope body portion.

12. A cathode-ray tube envelope in accordance with claim 1l wherein said first reinforcing band is comprised of a pair of similar U-shaped half-sections integrally joined at diametrically-opposed locations and having a circumferential extent slightly less than the surrounded peripheral sidewall portion of said viewing member at ambient temperatures.

13. A cathode-ray tube envelope in accordance with claim 11, including a continuous annular layer of reacted synthetic resin adhesive materials substantially filling said circumferential space and integrally bonding said first reinforcing band to said surrounded peripheral sidewall region.

14. A reinforced cathode-ray tube envelope comprising a substantially funnel-shaped hollow glass body portion and a light-transmitting viewing portion sealed to and enclosing its larger end, said viewing yportion having an integral peripheral sidewall surrounding the viewing area with an annular recess in its non-viewing exterior surfaces, at least one endless reinforcing band of thin-walled, hightensile strength material surrounding the peripheral sidewall of said viewing portion having sufcient width to fully enclose said annular recess and complementally contoured to conform to exterior surfaces adjacent said recess, said reinforcing band being maintained in continuous tension to introduce compressive stresses into the peripheral sidewall therebeneath, and at least one access opening leading into said recessed area to facilitate the introduction of adhesive material thereinto subsequent to mounting said band.

15. A cathode-ray tube envelope in accordance with claim 14 wherein a continuous annular layer of adhesive material essentially fills the circumferential space formed by said annular recess and said reinforcing band.

16. A cathode-ray tube envelope in accordance with claim 14 including a second annular band contacting and surrounding at least a portion of said reinforcing band, said second band being maintained in continuous tension.

f7. A face plate for a cathode-ray tube envelope comprising a viewing portion and an integral peripheral sidewall portion, at least one endless reinforcing band of thinwalled high-tensile strength material surrounding said 4peripheral sidewall and complementally contoured to conform snugly to its forwardmost non-viewing region,

said reinforcing band being maintained in continuous tension to introduce compressive stresses into the peripheral sidewall therebeneath, a circumferential open annulus located intermediate said band and the exterior surfaces of said peripheral sidewall therebeneath, and at least one access opening into said open annulus to facilitate the introduction of adhesive material thereinto subsequent to mounting said band.

18. A face plate in accordance with claim 17, wherein an annular recess is provided in the internal surface of said endless reinforcing band to form said open annulus.

19. A face plate in accordance with claim 17, wherein an annular recess is provided in the external surface of said envelope peripheral sidewall portion adjacent its forwardmost non-viewing region to form said open annulus.

20. A face plate in accordance with claim 17, including a plurality of access openings disposed in spaced-apart symmetrical relation within said reinforcing band.

21. A face plate for a cathode-ray tube envelope, comprising a light-transmitting viewing portion and an integral peripheral non-viewing sidewall portion, at least one endless reinforcing band of thin-walled high-tensile strength metal surrounding said peripheral sidewall portion and complementally contoured to conform snugly to the forwardmost non-viewing sidewall portion, said contoured reinforcing band having at least one annular recess in an inner surface to provide a circumferential space extending transversely of the face plate axis intermediate said band and the exterior surfaces of said sidewall portion therebeneath, said reinforcing band being maintained in continuous tension to introduce compressive stresses into said peripheral sidewall portion therebeneath, said contoured band having at least one access opening extending into said annular inner recess to facilitate the introduction of adhesive means interiorly of said circumferential space.

22. A cathode-ray tube in accordance with claim 21 wherein said viewing member has a generally rectangular configuration and means are provided for maintaining the space between said band and said sidewall exterior surface in the corner regions of said rectangular viewing member.

23. A face plate in accordance with claim 21 wherein haid reinforcing band is comprised of a pair of similar -shaped half-sections integrally joined at diametricallyopposed locations and having a circumferential extent slightly less than the surrounded peripheral sidewall portion at ambient temperatures.

24. A face plate in accordance with claim 21 including a second discontinuous reinforcing band surrounding an annular rearward portion of said rst contoured reinforcing band, both said bands being mounted entirely forwardly of said envelope body member, said second reinforcing band being maintained in continuous tension to maintain said first band in snug conformity to said peripheral sidewall portion.

25. A face plate for a cathode-ray tube envelope comprising a light-transmitting glass viewing portion and an integral peripheral non-viewing sidewall portion, a rst endless metallic reinforcing band closely surrounding said sidewall portion complementally contoured to conform snugly to the exterior surface thereof and disposed normal to its axis, said rst reinforcing band having at least one beaded region of enlarged exterior dimensions extending annularly to provide a circumferential space intermediate said band and the exterior surfaces of said non-viewing periphery therebeneath, a series of exteriorly-opening apertures in the beaded region of said rst reinforcing band to facilitate the introduction of .adhesive material within said circumferential space, a second discontinuous metallic reinforcing band surrounding at least an annular rearward portion of said rst band, and means for maintaining said second band in continuous tension.

26. A reinforced face plate for a cathode-ray tube en velope comprising a light-transmitting viewing portion and an integral peripheral sidewall surrounding said viewing portion, said peripheral sidewall having an annular recess in its non-viewing exterior surfaces, at least one endless reinforcing band of thin-walled, high-tensile strength material surrounding the peripheral sidewall having suicient width to fully enclose said annular recess and complementally contoured to conform to exterior surfaces adjacent said recess, said reinforcing band being maintained in continuous tension to introduce compressive stresses into the peripheral sidewall therebeneath, and at least one access opening leading into said recessed area to facilitate the introduction of adhesive material thereinto subsequent to mounting said band.

27. A face plate in accordance with claim 26 including a second annular band contacting and surrounding at least a portion of said reinforcing band, said second band being maintained in continuous tension.

References Cited by the Examiner UNITED STATES PATENTS 2,785,820 3/1957 Vincent et al 2202.1 3,037,834 6/1962 Lederer 316-l9 3,041,127 6/1962 Turnbull 316-19 3,162,933 12/1964 Trax et al. 29--155.5 3,166,211 1/1965 Stel et al. 220-2.1

THERON E. CONDON, Primary Examiner. M. L. RICE, Assistant Examiner. 

1. AS AN ARTICLE OF MANUFACTURE, A CATHODE-RAY TUBE ENVELOPE COMPRISING A SUBSTANTIALLY FUNNEL-SHAPED HOLLOW BODY MEMBER AND A LIGHT-TRANSMITTING VIEWING MEMBER ENCLOSING ITS LARGER END, SAID VIEWING MEMBER HAVING AN INTEGRAL PERIPHERAL SIDEWALL PORTION OF SUBSTANTIALLY MAXIMUM CROSS-SECTIONAL DIMENSIONS OF SAID ENVELOPE SEALED TO THE LARGER END OF SAID BODY MEMBER, AT LEAST ONE ENDLESS REINFORCING BAND OF THIN-WALLED HIGH-TENSILE STRENGTH MATERIAL SURROUNDING THE PERIPHERAL SIDEWALL PORTION OF SAID VIEWING MEMBER AND COMPLEMENTALLY CONTOURED TO CONFORM SNUGLY TO ITS FORWARDMOST NON-VIEWING REGION, SAID REINFORCING BAND BEING MAINTAINED IN CONTINUOUS TENSION TO INTRODUCE COMPRESSIVE STRESSES INTO THE PERIPHERAL SIDEWALL PORTION THEREBENEATH, A CIRCUMFERENTIAL OPEN ANNULUS LOCATED INTERMEDIATE SAID BAND AND THE EXTERIOR SURFACES OF SAID ENVELOPE SIDEWALL PORTION THEREBENEATH, AND AT LEAST ONE ACCESS OPENING INTO SAID OPEN ANNULUS TO FACILITATE THE INTRODUCTION OF ADHESIVE MATERIAL THEREINTO SUBSEQUENT TO MOUNTING SAID BAND. 